As computers have become more complex, user interfaces have had to adapt to allow the user to control the operations of the computer. Initially, the interface used was a command line interface, which utilized a series of typed commands formatted in a specific syntax familiar to the computer and eventually learned by computer users. This interface was eventually replaced by the Graphical User Interface (“GUI”), which allows users to point to objects, buttons, and windows displayed like items on a desk. Initially, interaction between the GUI and a user was accomplished through a light pen, a pen-based computer control requiring the user to select and highlight objects on the screen by touching the light to the object on the screen. However, this implementation had its disadvantages because, by design, the user's hands and the light pen would obscure a portion of the screen from the user's own view. This and other disadvantages led to the development of the mouse, an interface control separate from the keyboard, that controlled a pointer on the GUI for selecting and highlighting objects, buttons, and windows.
The growth of the personal digital assistant (“PDA”) and wearable computer markets are associated with similar problems realized in the larger-scale computing systems. As PDA technology continues to rapidly advance with respect to the size of PDA electronics and batteries, the size of handheld and mobile devices becomes more dependent upon the user interface utilized.
One of the current and practiced methods of interaction between a user and a PDA is a stylus-based GUI. In stylus-based interaction, the user holds the device in one hand and the stylus in the other. A stylus-based GUI enables a user to take full advantage of the PDA by allowing the user to navigate through applications operating on a computing system, control operations associated with those applications, and input text while using only one selection device—the stylus. In short, a separate keyboard or other input device is not needed.
While such interaction is similar to the use of a conventional pad and paper, it is not without problems. Since the stylus-based GUI is a simple derivation of the former light pen, it includes many of the same problems associated with the light pen-based GUI's. The use of a stylus obscures the portion of the display that the writing hand is covering. Further, the stylus-based GUI requires two-hand operation and typically requires the user to look at the device while using it. The stylus-based GUI must also include complex software to recognize the user's handwriting.
Another current and practiced method of interaction between a user and a PDA is the use of a numeric keypad, where each number key includes various letters of the Roman alphabet. Wireless and other similar devices also used such numeric keypads to allow a user to interact with the devices. The design of the numeric keypad allows a user to input text and/or numbers to initiate some operational element of the PDA. The use of the numeric keypad generally requires the user to use one hand to accomplish the interaction, which is advantageous over the stylus-based interaction method.
Unfortunately, the current and practiced method of interaction using a numeric keypad does not function with languages that are not based upon the Roman alphabet. In particular, the English language is generally written using an alphabet of twenty-six letters derived from the Romans. Other written languages, however, may employ significantly greater numbers of written characters. An example of a written language that requires a relatively large number of written characters is the Chinese language. Chinese has a constrained phonetic structure. In spoken Chinese, there are only 412 basic phonetic units, each unit having a monosyllabic sound. Four sound patterns can potentially be applied to each phonetic unit, resulting in slightly more than 1,000 distinct sounds. Other languages not based on the Roman alphabet also include a vast number of characters, and may also employ the use of monosyllabic sounds. Put simply, current numeric keypads are not capable of handling the large number of written characters of those languages that use a non-Roman based lettering system.